Dose-determinate exposures of gravid mice and rats to 2450-MHz and 915-MHz microwave energy would be performed in studies of lethal-dosing, teratology, longevity, and maze-learning. Corollary studies would: 1) evaluate the role of endogenous (psychogenic) heating in mammals as induced by handling and restraint in lethality of dosing; 2) examine growth and ultrastructure of a thermophilic organism that exhibits retarded growth and hyperplasia of the plasma membrane under microwave radiation; 3) record the ethogram of an avian species previously incubated in a microwave field; 4) determine the utility of evoked thermal responses as indicators of perception of microwave energy; and 5) yield evidence on the use of hypothermal agents in mammals in the quest for a biodosimeter of absorbed electromagnetic energy. The multi-mode cavity would be used for exposing organisms to microwave energy and attempts would be made to compare effects of continuous wave (CW) vs. pulsed radiations of the same averaged density.